Rock drill bit



. g.1s,19s6. J.H.HOWARD 2 051,525

ROCK DRILL BIT Filed Nov. 1'7, 1933 Affa'wey Patented Aug. 18, 1936 PATENT OFFICE;

ROCK DRILL BIT John E. Howard, Huntington Park, CaliL, as-

signor to Globe Oil Tools Company, Los Nictos, Calii., a corporation or California Application November H, 1933, Serial No. 698,419

3 Claims. (01. 255-64) This invention relates. to a drilling tool, and relates more particularly to a rock drill bit. It is a general object of the invention to provide an improved rock drill bit having an efiective cutting head that is readily detachable from its shank.

It is another object of the invention to provide a percussive rock drill bit having a durable eflicient cutting head that is self-sharpening through use.

It is another object, oi! the invention to provide a rock drill bit including a cutting head that may be easily and quickly removed train the stem or shank ior resharpening or replacement. i

It is another object of the invention to provide a simple, practical and eilective means for detachably connecting thecutting head of a rock drill with its shank.

It is another object 0! the invention to provide a rock drill bit including a detachable cutting head that is removably attached to the shank in a secure and dependable manner so that it cannot be separated from the shank in the drilled hole or bore.

It is another object of the invention to provide an improved cutting head for a rock drill bit having a plurality of effective cutting edges and plane faces or surfaces that have a crushing and pulverizing action during operation of the bit.

It is a further object of the invention to provide a rock drill bit of the character mentioned that is simple and inexpensive of manufacture, and that does not embody any parts that may become lost or detached during operation of the bit.

Other objects and features 02 the invention will be readily and fully understood from the following detailed description of a typical form of the invention, throughout which description reference may be had to the accompanying drawing in which:

Fig. 1 is a side elevation of the bit provided by the invention. Fig. 2 is a side elevation of the shank'with the cutting removed. Fig. 3 is a longitudinal detailed sectional view of the bit with one of the wedges removed. Fig. 4 is a transverse sectional view taken'as indicated by line 4-4 on Fig. 3, and Fig. 5 is a bottom elevation of the cutting head.

the passage I 8 to the bevelled corners 2!.

The drill rod or shank III which is similar generally to the rods or shanks of typical rock bits is an elongate member adapted to be operated by a jack hammer or pneumatic drilling machine. The shank' It! is provided at its lower end to handle circulation fluid.

The cutting head It is removably mounted on or attached to the enlarged portion i3 of the shank iii, and is provided to act on, or cut the rock or material being drilled. A longitudinal socket it extends into the upper end of the cut-v ting head iii for the reception of the enlarged portion I3 of the shank. The bottom wall i! of the socket i6 is preferably flat to evenly cooperate with' the lower end [4 of the shank whereby the percussive drilling action may be directly transmitted from the shank iii to the cutting head. A central longitudinal fluid passage or port i8 is provided in the cutting head it to register with the lower end of the passage i5, and to'discharge from the lower end of the head.

In accordance with the invention the active lower portion I 9 of the cutting head II is substantially rectangular in horizontal cross section, and is of increased width and of substantial thickness. The enlarged lower portion I9 01' the cutting head H has four flat sides 20. The corners 2| oi the enlarged portion IQ of the cutting head are flattened or bevelled, as illustrated throughout the drawing, providing reaming edges 22. The flattened corners 2| may be inclined upwardly and inwardly to have cutting clearance. The lower end of the cutting head it is provided with four cutting edges 23 which extend radially outward from-the lower end of Two pairs of pitched or downwardly and inwardly inclined iiat i'aces 24 and 25 are presented at the lower end of the cutting head. The faces Hand 25 are presented at the lower end of the cutting head. The faces 24 and 25 are substantially triangular and join at the radial cutting edges 23. The pairs of. faces 24 and 25 join the sides 20 of the head H at edges 26. outer edges 26 of the several faces 24 and 25 all lie in a common plane'normal to the longitudinal axis of the bit. As the enlarged por- The upper or tion I! of the head II is rectangular, the faces 24 are pitched at a greater angle to the longitudinal axis of the bit than the faces 25. This relationship between the pitch or inclination of the pairs of faces 24 and 25 provides for the self-sharpening of the cutting edges 23 during operation of the bit. The flat plane surfaces or faces 24 and 25 have an effective crushing and pulverizing action on the rock or material drilled.

The means l2 for removably attaching the cutting head H to the shank III is a feature of the invention, and is such that thehead ll may be easily and quickly detached from the shank III for replacement, resharpening, etc. The detachable connecting means l2 includes a thread 30 on the wall of the socket l6, and a thread 3| on the enlarged portion l3 of the shank for meshing with'or cooperating with the thrcad13ll. The threads 30 and 3| .are preferably comparatively heavy, and in accordance with the invention are of substantial pitch so as to be easily unthreaded. In the particular case illustrated in the drawing, the threads 30 and 3! are left hand threads. It will be apparent how the cutting head ll may be easily and quickly threaded onto the enlarged portion l3 of the shank to have the bottom I! of the socket I bear against the lower end l4 of the The means l2 includes one or more wedges 32 for positively preventing detachment or unthreading of the head II from the shank l3 during use of the bit. In the typical form of the invention illustrated in the drawing, there are two like wedges 32 provided for locking the head II on the shank. The threads 30 and 3| are, broken or cut away to provide two diametrically opposite longitudinal openings or channels 34 for receiving the wedges 32. The shank portion l3 and the wall of the socket l6 may be flattened where the threads are cut away. Each wedge 32 has a straight or vertical side 36 for cooperating with the ends 35 of the thread 3| of the shank, and a longitudinal side 31 that is inclined downwardly and rearwardly relative to the direction of pitch of the threads for cooperating with the ends 35 of the thread 33 on the wall of the socket It. The ends of the thread 33 engaged by the-iriclined sides of the wedges are preferably pitched in the same manner as the said sides of the wedge. The wedges 32 are proportioned and related to the channels 34 to cooperate with the ends '35 of the thread 33 when driven into the channels 34 so as to urge or tend to further thread the cutting head ll onto the shank. This function or operation of the wedges 32 assures a tight dependable connection between the cutting head II and the shank. The wedges 30 are adapted to be forced or driven downwardly into the channels 34 from the upper end of the cutting head ll. Outwardly projecting heads 39 are provided on the wedges to facilitate the removal of the wedges, as will be subsequently described.

The invention includes means for releasably locking the wedges 32 against. movement and displacement. Lateral openings 43 are provided in the wall of the cutting head II to communicate with the lower ends of the channels 34. Downwardly and outwardly inclined shoulders 4! are provided on the shank l0 opposite or directly opposing the openings 40. When-the wedges 32 are forced or driven downwardly tions are diverted or bent outwardly into the openings 40. These outwardly bent lower portions 42 of the wedges 32 cooperate with the openings 40 to dependably lock the keys 32 against upward movement out of the channels 34. The portions of the wedge 42 while they do not project from the cuttinghead II, are accessible for engagement by a drift or punch whereby the wedges 32 may readily be driven out of the channels 34 when detaching the cut- .ting head II from the shank.

Itis believed that the utility and practicability of the rock drill bit of the present invention will be readily apparent from the foregoing detailed description. In applying or attaching the cutting head H to the shank ID, the head is first threaded onto the enlarged portion l3 of the shankso that the bottom wall ll of the socket l3 comes into bearing engagement with the lower end I 4 of the shank. With the faces l4 and I] in engagement, the openings 40 are in alignment with the shoulders 4| at the lower ends of the channels 34. The wedges 32 may be readily driven or forced downwardly into the channels 34, and when their lower ends engage.

the shoulders 4|, their lower portions 42 are deflected or bent outwardly into the openings 43. This, of course, dependably retains or locks the wedges 32 in position. The inclined edges or sides 31 of the'wedges 32 engage or contact with the ends 35 of the thread 30 to urge or tighten the cutting head II on to the pin, and to dependably prevent loosening of the head from the shank during the drilling operation. Thecutting head II is particularly rapid and efllcient in its cutting action. The inclinations or pitches of the pairs of faces 24 and 25 provide for a self-sharpening of the cutting edges 23. The

flat faces 24 and 25 operate to cmsh or pulverize the rock.

when it is desired to detach the cutting head ll from the shank III, the wedges 32 are first driven upwardly out of the channels 34. The wedges 32 may be readily driven out by engaging their lower. ends through the opening 40" with a suitable driving too], or by driving up wardly under the heads 39. Driving or forcing the wedges outwardly in this manner, of course, straightens their bent portions 42, and allows the wedges to be readily withdrawn from the.

channels 34. After the wedges 32 have been removed, the cutting head ll may be easily'unthreaded from the enlarged portion 13 of the 1 shank. The rock drill bit provided by my-invention is simple and inexpensive of manufacture and embodies an improved cutting head that may be easily and quickly detached from the shank when desired or necessary. I

.Having described only a typical form or embodiment of the invention, I do not wish to limit myself to the specific details set forth, but wish to reserve to myself any changes or variations,

head having a socket for receiving an end por-' tion of the shank, a thread on said portion of the shank, a thread on thewall of the socket for cooperating with the first mentioned thread to removably attach the head to the shank, the

threads having registering cut-away portions leaving an opening, there being a lateral opening in the head communicating with .the first named opening, the ends of the threads at the corresponding sides of the cut away portions being inclined, a wedge in the opening engaging said ends of the threads to urge the head in the thread-tightening direction, and a part on the inner end of the wedge projecting into said lateral opening to hold the wedge in position.

2. A rock drill bit including a shank, a cutting head having a socket for receiving an end portion of'the shank, a thread on said portion of the shank, a thread on the wall of the socket for cooperating withthe first mentioned thread to removably attach the head to the shank, the threads having registering cut-away portions leaving an opening, there being a lateral opening in the head communicating with the first mentioned opening, and a wedge in the first mentioned opening having wedging cooperation with the threads to prevent unthreading of the head and having a bent end part cooperating with the lateral opening whereby it is held in position.

3. A drilling bit including, a shank, a thread on the lower portion of the shank having a longitudinal cut-away part, the ends of the thread at one side of the cut away part being inclined with respect to the longitudinal axis of the shank, a cutting head having a socket for receiving the lower portion of the shank, a thread on the wall of the socket for cooperating with the first mentioned thread and having a longitudinal cut-away part, the ends of the socket thread at one side of the cut away part being inclined with respect to the longitudinal axis of the socket, said cut-away parts of the threads being related to register and form an opening, the head having a lateral opening communicating with the inner end portion of the first named opening, a wedge in said first named opening preventing unthreading of the head from the shank and having a tapered side cooperating with the inclined ends of the threads to urge an end portion on the wedge projecting into said lateral opening to prevent loss of the wedge.

' JOHN H. HOWARD.

the head in the thread-tightening direction and 20 

